Looks to me - when I squint - that the muzzle shot has a 1901, and the sentry an 1898 or 1902.

And, FWIW, while all of the kudos in the world are due to 5MF for his herculean efforts, sometimes I cannot, no matter how hard I try, follow his logic. He may very well be right (and I hope he is) as regards Whig's rifle, but I do not know what (specifically) tells him that.